The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
In a spark ignition engine, a mixture of fuel and air enters the piston combustion chamber during an intake process. The air/fuel mixture is compressed and combustion is initiated with a high energy electric spark during an ignition process.
Ignition timing impacts the performance, longevity, power, and the fuel economy of an engine. Under certain conditions uncontrolled or automatic ignitions (AI) can occur. Uncontrolled ignitions occur in spark-ignition engines when an air/fuel mixture in a cylinder is ignited by an ignition source other than spark. Generally, uncontrolled ignition that occurs before TDC is referred to Auto-Ignition (AI).
Uncontrolled ignition occurring too soon or too late in the combustion cycle is often responsible for excessive vibrations and can potentially cause engine damage due to increased cylinder temperature and pressure. Engine control systems monitor a position of a crankshaft of an engine as a means to determine crank angle. Crank angle is useful in determining when an AI event is occurring. To preserve an engine's longevity, it is important to determine when AI is occurring and take remedial action.
While detecting and mitigating systems for uncontrolled ignitions occurring after TDC are known in the art and achieve their intended purpose there still remains a need for improved detection and mitigation systems and methods. More specifically, there is a need for a new and improved detection and mitigation system identifying auto ignitions before TDC in spark ignition engines.